Classifying Numbers by Their Properties
Primary 4 · Mathematics
Classifying Numbers by Their Properties
Lesson 2 of 5
25 min
Let's begin
Mutesi is making bags of sweet potatoes to sell at the market in Nyamata. She has 12 sweet potatoes and wants every bag to hold the same number, with none left over. She could make 1 bag of 12, 2 bags of 6, 3 bags of 4 … How many different ways are there?
The multiples of a number are the answers in its times table. Skip count to find them.
The list of multiples never ends.
A factor of a number divides it exactly, with no remainder. You can find factors by building rectangles. Every rectangle made from 12 squares gives a factor pair:
The factors of 12 are 1, 2, 3, 4, 6 and 12. So Mutesi can make 1, 2, 3, 4, 6 or 12 equal bags: six different ways.
Start at 1 and work upwards, testing each number. For 30:
Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30.
3 × 4 = 12, so 3 and 4 are factors of 12, and 12 is a multiple of 3 and of 4.
Practise: play the Factor game in the Arithmetic simulation. It shows you a product and you find the two factors.
Tip
Factors are few, multiples are many. A number has only a few factors, and none is bigger than the number itself. Its multiples go on for ever.
Work each one in your exercise book first. Then tap Show answer to check.
Write the first five multiples of 7.
Answer: 7, 14, 21, 28, 35
List all the factors of 30.
Answer: 1, 2, 3, 5, 6, 10, 15, 30
Is 5 a factor of 42?
Answer: No. 42 ÷ 5 = 8 remainder 2.
Is 56 a multiple of 8?
Answer: Yes, because 8 × 7 = 56.
Write all the factor pairs of 20.
Answer: 1 × 20, 2 × 10, 4 × 5
What you learned today
Sources and credits
The stories, Rwandan worked examples, diagrams and practice questions were written by Ganzaa.
Quick check
Which number is a multiple of 6?
